Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrograph

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) will observe approximately 100,000 giant stars in the Milky Way with a dedicated fiber-fed (300 fibers from the Sloan 2.5-m telescope) near-infrared (1.5-1.7 micron) high resolution (R 22,500) spectrograph as part of the Sloan Digital Sky Survey III (SDSS-III). By observing in the near-infrared, APOGEE can uniformly sample all Milky Way stellar populations (bulge, thin/thick disks and halo) in the same survey to dramatically improve our understanding of the kinematical and chemical enrichment history of our galaxy. The instrument design includes several innovations: a novel fiber gang connector that allows simultaneous optical connection of 300 fibers from the instrument into swappable plug plate cartridges, the first deployed mosaic volume phase holographic (VPH) grating, and a very large ( 0.4-m) aperture six-element refractive camera incorporating crystalline silicon elements to image 300 spectra onto three HAWAII-IIRG detectors simultaneously.